The present invention is directed to a bone marrow aspirator and methods of use thereof.
Numerous medical conditions require extracting bone marrow from a patient. Such conditions include, but are not limited to, leukemias, brain tumors, breast cancer, hodgkin's disease, neuroblastoma, and ovarian cancer. Further, a wide spectrum of procedures require bone marrow. For example, bone marrow may be needed for spinal fusion, non-union fractures, revisions of total hip and knee arthroplasty procedures in which severe bone marrow loss is encountered, as well as numerous other procedures. Further still, some diagnostic tests require samples of bone marrow. For example, marrow samples may be needed to better understand the cause of abnormal blood test results, confirm a diagnosis or check the status of severe anemia of unknown cause, evaluate abnormalities in the blood's ability to store iron, diagnose infection, or marrow samples may be needed for numerous other tests.
Typically, bone marrow is extracted from the patient's iliac crest. To extract marrow, a needle is passed through the soft tissue and cortical bone of a patient and pushed into the cancellous bone. In the cancellous bone, bone marrow is extracted through the needle. The current techniques typically involve penetrating numerous sites in the bone until enough bone marrow is extracted to either treat the condition, perform the procedure, or complete the test.
A current method of aspirating bone marrow consists of driving a needle connected to a syringe into either the anterior or posterior regions of the iliac to a depth relatively proximal i.e. (closest to the cortical surface). As the plunger of the syringe is retracted to generate the necessary vacuum required for aspiration, the needle is slowly rotated 360° in order to collect marrow from a circumferential region about the tip of the needle. Enabling this circumferential collection is a needle that has a side port on its wall adjacent to the tip, and a closed, pointed tip. Upon full collection of marrow at that site, the needle is driven more distally (i.e. deeper) and coupled to a new syringe and the process repeated again. A third depth may be used providing the patient's anatomy is large enough to accommodate the length of the needle without perforating through the distal wall of the iliac crest.
The reason the needle is rotated during aspiration at multiple depths is that bone marrow does not flow easily due to its viscosity and bone to the adjacent trabecular structures. Unlike blood which can flow easily from areas remote to the injection site through capillary action, marrow can only be collected from the general vicinity of the port of the needle. Once that limited marrow space is evacuated, peripheral blood will rush in and flow into the syringe. This is not desirable since the blood will dilute the concentration of stem cells per unit volume of aspiration. Human and animal study data (George F. Muschler et al. JBJS 79:1699-1709, 1997) suggests that for the highest stem cell concentration results, the aspiration volume should not exceed 2 ccs for every centimeter of linear travel of the needle. Using a manual process to control the collected volume and location of the needle results in a procedure that is very technique dependent and yields inconsistent results.
In order to extract an adequate sample, doctors may insert the needle into several different parts of the iliac crest. In some cases this requires a multitude of insertions (e.g., six or even more for leukemia patients). The above described methods can be extremely painful for a patient and in some cases deters individuals from donating bone marrow and deters patients from undergoing a necessary bone marrow test.
Accordingly, a need exist for a bone marrow aspirator and method thereof that increases the efficiency in obtaining bone marrow from a patient. Thereby minimizing patient discomfort.